Aqueous polymer emulsion

Abstract

The present invention relates to an aqueous emulsion comprising at least 30 wt. % of vinyl copolymer(s) (A), said vinyl copolymer(s) (A) containing the following monomers: (I) isobornyl methacrylate and 2-octyl acrylate in a summed amount of at least 30 wt. %, in a weight ratio of isobornyl methacrylate to 2-octyl acrylate from 5:95 to 95:5; (II) no more than 70 wt. % of at least one ethylenically unsaturated monomer other than 2-octyl acrylate and isobornyl methacrylate, whereby the summed amount of (I) and (II) is 100 wt. % and whereby the amount of vinyl copolymer(s) (A) is given relative to the total weight amount of binder present in the emulsion.

1 . An aqueous emulsion comprising at least 30 wt. % of vinyl copolymer(s) (A), said vinyl copolymer(s) (A) containing the following monomers:
 (I) isobornyl methacrylate and 2-octyl acrylate in a summed amount of at least 30 wt. %, in a weight ratio of isobornyl methacrylate to 2-octyl acrylate from 5:95 to 95:5;   (II) no more than 70 wt. % of at least one ethylenically unsaturated monomer other than 2-octyl acrylate and isobornyl methacrylate,   whereby the summed amount of (I) and (II) is 100 wt. % and whereby   the amount of vinyl copolymer(s) (A) is given relative to the total weight amount of binder present in the emulsion.   
     
     
         2 . An emulsion according to  claim 1 , wherein the vinyl copolymer(s) (A) contains
 (I) isobornyl methacrylate and 2-octyl acrylate in a summed amount of at least 40 wt. %, in a weight ratio of isobornyl methacrylate to 2-octyl acrylate from 5:95 to 95:5;   (II) no more than 60 wt. % of at least one ethylenically unsaturated monomer other than 2-octyl acrylate and isobornyl methacrylate,   whereby the summed amount of (I) and (II) is 100 wt. %.   
     
     
         3 . An emulsion according to  claim 1 , wherein the weight ratio of isobornyl methacrylate to 2-octyl acrylate is from 15:85 to 85:15. 
     
     
         4 . An emulsion according to  claim 1 , wherein the glass transition temperature of the vinyl copolymer(s) (A) is in the range from −30° C. to 80° C., whereby the glass transition temperature is determined according to the method as disclosed in this specification. 
     
     
         5 . An emulsion according to  claim 1 , wherein the amount of vinyl copolymer(s) (A) present in the emulsion is 100 wt. %, relative to the total weight amount of binder present in the emulsion, and the monomers (II) in the vinyl copolymer(s) (A) contains the following monomers
 (IIa) from 0.1 to 10 wt. %, preferably from 0.1 to 5 wt. % of carboxylic acid functional ethylenically unsaturated monomer(s);   (IIb) from 0 to 5 wt. % of ethylenically unsaturated crosslinkable monomer, different from (IIa);   (IIc) from 0 to 5 wt. % of ethylenically unsaturated wet adhesion promotor monomer, different from (IIa) and (IIb);   (IId) from 50 to 69.9 wt. %, preferably from 55 to 69.9 wt. % of ethylenically unsaturated monomer(s), different from (IIa), (IIb) and (IIc);   whereby the amounts of (IIa), (IIb), (IIc) and (IId) are given relative to the total amount of (I) and (II).   
     
     
         6 . An emulsion according to  claim 2 , wherein the amount of vinyl copolymer(s) (A) present in the emulsion is 100 wt. %, relative to the total weight amount of binder present in the emulsion, and the monomers (II) in the vinyl copolymer(s) (A) contains the following monomers
 (IIa) from 0.1 to 10 wt. %, preferably from 0.1 to 5 wt. % of carboxylic acid functional ethylenically unsaturated monomer(s);   (IIb) from 0 to 5 wt. % of ethylenically unsaturated crosslinkable monomer, different from (IIa);   (IIc) from 0 to 5 wt. % of ethylenically unsaturated wet adhesion promotor monomer, different from (IIa) and (IIb);   (IId) from 40 to 59.9 wt. %, preferably from 45 to 59.9 wt. % of ethylenically unsaturated monomer(s), different from (IIa), (IIb) and (IIc);   whereby the amounts of (IIa), (IIb), (IIc) and (IId) are given relative to the total amount of (I) and (II).   
     
     
         7 . An emulsion according to  claim 5 , wherein monomer (IIa) is acrylic acid and/or methacrylic acid. 
     
     
         8 . An emulsion according to  claim 5 , wherein monomers (IIb), (IIc) and (IId) are selected from the group consisting of acrylates, methacrylates, arylalkylenes and any mixture thereof. 
     
     
         9 . An emulsion according to  claim 5 , wherein monomer (IId) is selected from the group consisting of methyl (meth)acrylate, ethyl (meth)acrylate, butyl (meth)acrylate, styrene and combinations thereof. 
     
     
         10 . An emulsion according to  claim 5 , wherein the vinyl copolymer(s) (A) do not contain monomer (IIb) and/or monomer (IIc). 
     
     
         11 . An emulsion according to  claim 5 , wherein the glass transition temperature of the vinyl copolymer(s) (A) is in the range from 20° C. to 60° C., preferably in the range from 40° C. to 60° C., whereby the glass transition temperature is determined according to the method as disclosed in this specification. 
     
     
         12 . An emulsion according to  claim 5 , wherein the glass transition temperature of the vinyl copolymer(s) (A) is in the range from −20° C. to 20° C., whereby the glass transition temperature is determined according to the method as disclosed in this specification. 
     
     
         13 . An emulsion according to  claim 1 , wherein the emulsion comprises a first vinyl copolymer (A1) and a second vinyl copolymer (A2), both containing monomers, whereby the first vinyl copolymer (A1) is obtained by emulsion polymerization and the second vinyl copolymer (A2) is obtained by emulsion polymerization in the presence of the first vinyl copolymer (A1) and whereby the glass transition temperature of the vinyl copolymer (A1) is in the range from −20° C. to 20° C. and the glass transition temperature of the vinyl copolymer (A2) is in the range from 60° C. to 120° C., whereby the glass transition temperature is determined according to the method as disclosed in this specification. 
     
     
         14 . An emulsion according to  claim 1 , wherein the emulsion further comprises at least one second polymer (B) different from vinyl copolymer (A), whereby the weight ratio of vinyl copolymer(s) (A) to polymer(s) (B) is in the range from 90:10 to 50:50 and whereby the total amount of vinyl copolymer(s) (A) and polymer(s) (B) present in the emulsion is 100 wt. %, relative to the total weight amount of binder present in the emulsion. 
     
     
         15 . An emulsion according to  claim 14 , wherein the second polymer (B) is a vinyl copolymer (B); the vinyl copolymer (A) and vinyl copolymer (B) are obtained by a process comprising steps:
 a) a first polymerization step, to form the vinyl copolymer (A);   b) a second polymerization step effected in the presence of the resulting first phase vinyl copolymer (A) obtained in step a) to form the second phase vinyl copolymer (B).   
     
     
         16 . An emulsion according to  claim 14 , wherein monomer (II) in the vinyl copolymer (A) contains from 0.1 to 15 wt. %, preferably from 0.1 to 10 wt. %, more preferably from 1 to 5 wt. % of carboxylic acid functional ethylenically unsaturated monomer, whereby the amount of carboxylic acid functional ethylenically unsaturated monomer is given relative to the total amount of (I) and (II). 
     
     
         17 . An emulsion according to  claim 16 , wherein the vinyl copolymer (B) contains the following monomers:
 (IB) from 0.1 to 10 wt. %, preferably from 0.1 to 5 wt. %, more preferably from 1 to 3.5 wt. % of carboxylic acid functional ethylenically unsaturated monomer;   (IIB) from 90 to 99.9 wt. %, preferably from 95 to 99.9 wt. %, more preferably from 96.5 wt. % to 99 wt. % of ethylenically unsaturated monomer, different from (IB);   whereby the amounts of (IB) and (IIB) are given relative to the total weight amount of monomers used to prepare the vinyl copolymer (B).   
     
     
         18 . An emulsion according to  claim 17 , wherein monomers (IIB) are selected from the group consisting of acrylates, methacrylates, arylalkylenes and any mixture thereof. 
     
     
         19 . An emulsion according to  claim 14 , wherein the second polymer (B) is a vinyl copolymer (B) and the vinyl copolymers (A) and (B) are obtained by a process comprising steps:
 a) preparing a first phase carboxylic acid-functional vinyl copolymer (B) by emulsion polymerization of a monomer composition B in the presence of a chain-transfer agent, whereby monomer composition B contains:
 Bi) at least one carboxylic acid functional ethylenically unsaturated monomer; and 
 Bii) at least one ethylenically unsaturated monomer different than Bi); and 
   b) preparing a second phase vinyl copolymer (A) by emulsion polymerization of a monomer composition A in the presence of the resulting first phase vinyl copolymer (B) from step a) where the monomer composition A contains the following monomers:
 (I) isobornyl methacrylate and 2-octyl acrylate in a summed amount of at least 30 wt. %, in a weight ratio of isobornyl methacrylate to 2-octyl acrylate from 5:95 to 95:5; 
 (II) no more than 70 wt. % of at least one ethylenically unsaturated monomer other than 2-octyl acrylate and isobornyl methacrylate, whereby the summed amount of (I) and (II) is 100 wt. %; 
   where the acid value of vinyl copolymer (A) is lower than the acid value of vinyl copolymer (B); the weight average molecular weight (Mw) of vinyl copolymer (A) is higher than the weight average molecular weight (Mw) of vinyl copolymer (B); and   where at least part of the carboxylic acid groups of vinyl copolymer (B) are deprotonated to obtain ionic or potentially ionic water-dispersing groups prior to step b).   
     
     
         20 . An emulsion according to  claim 15 , wherein the glass transition temperature of vinyl copolymer (B) is higher than the glass transition temperature of vinyl copolymer (A), whereby the difference in glass transition temperature between vinyl copolymer (B) and vinyl copolymer (A) is preferably at least 20° C., more preferably at least 30° C., even more preferably at least 40° C., whereby the glass transition temperature is determined according to the method as disclosed in this specification. 
     
     
         21 . An emulsion according to  claim 15 , wherein the glass transition temperature of the vinyl copolymer (A) is in the range from −20° C. to 20° C., whereby the glass transition temperature is determined according to the method as disclosed in this specification. 
     
     
         22 . An emulsion according to  claim 1 , wherein the weight average molecular weight of vinyl copolymer (A) is higher than 50,000 g/mol, more preferably higher than 80,000 g/mol, even more preferably higher than 200,000 g/mol; preferably lower than 10,000,000 g/mol and more preferably lower than 4,000,000 g/mol, whereby the weight average molecular weight is determined according to the method as disclosed in this specification. 
     
     
         23 . An emulsion according to  claim 19 , wherein vinyl copolymer (B) has a weight average molecular weight (Mw) less than 100,000 g/mole and higher than 2,000 g/mol, preferably less than 75,000 g/mol, more preferably less than 50,000 g/mol and the weight average molecular weight of vinyl copolymer (B) is most preferably from 10,000 to 35,000 g/mol, whereby the weight average molecular weight is determined according to the method as disclosed in this specification. 
     
     
         24 . An emulsion according to  claim 14 , wherein polymer (B) is a polyester, a polyesteramide, a polyamide or a polyurethane. 
     
     
         25 . An emulsion according to  claim 1 , wherein the emulsion comprises vinyl copolymer(s) (A) in an amount of at least 50 wt. %, more preferably of at least 70 wt. %, whereby the amount of vinyl copolymer (A) is given relative to the total weight amount of the binder present in the emulsion. 
     
     
         26 . A coating composition comprising an aqueous emulsion according to  claim 1  and further comprising solvents, pigments, dyes, heat stabilisers, defoamers, fillers, matting agents, UV absorbers and/or antioxidants. 
     
     
         27 . A coating composition according to  claim 26 , wherein the composition is a one-component, non-crosslinkable composition. 
     
     
         28 . A method of coating a substrate comprising applying a coating composition according to  claim 26  to a substrate and causing or allowing the aqueous carrier medium of the emulsion to be removed. 
     
     
         29 . A method according to  claim 28 , wherein the substrate is wood, optionally containing a primer and a midcoat, metal, plastic (for instance polypropylene or polyvinyl chloride), leather, glass, paper or a combination of at least two of these materials. 
     
     
         30 . A coated substrate obtained by the method of  claim 29 .